Previously, in a fuel supply device that is configured to supply fuel from an inside of a fuel tank of a vehicle to an internal combustion engine located at an outside of the fuel tank, the fuel, which is drawn from the fuel tank through a fuel pump, is discharged to the outside of the fuel tank.
A device of the patent literature 1, which serves as the fuel supply device described above, includes a suction filter, through which fuel is suctioned into a suction port of the fuel pump after filtering the fuel in the inside of the fuel tank. In the suction filter disclosed in the patent literature 1, a filter material, which serves as a filter screen and filters the fuel that permeates through the filter material, is placed to cover an inside space, into which a negative suction pressure is exerted from the suction port.
In the suction filter of the patent literature 1, when the fuel is forced and is displaced to one side in the fuel tank by an inertial force at a time of turning the vehicle or at a time of accelerating or decelerating the vehicle, the filter material is exposed from a surface of the fuel in the tank. Thereby, in the exposed state of the filter material, the fuel is suctioned from the inside space of the suction filter into the suction port and is thereby reduced in the inside space of the suction filter. In such a case, the air, the amount of which corresponds to the reduced amount of the fuel in the inside space of the suction filter, permeates through the filter material and is suctioned into the inside space of the suction filter. At this time, the inertial force of the fuel and the inertial force of the air are different from each other, and the air is more likely to move toward the suction port than the fuel. For this reason, the air is suctioned into the suction port in preference to the fuel. The preferential suctioning of the air deteriorates a suction efficiency of the fuel pump for suctioning the fuel into the suction port. Here, the deterioration of the suction efficiency of the fuel at the fuel supply device that supplies the discharged fuel, which is discharged from the fuel pump, to the internal combustion engine of the vehicle, may possibly cause drivability deterioration or engine stall and is thereby not desirable.